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	<head>
		<title>three.js webgl - level of detail</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">
	</head>

	<body>
		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - level of detail
		</div>

		<script type="module">

			import * as THREE from '../build/three.module.js';

			import { FlyControls } from './jsm/controls/FlyControls.js';

			let container;

			let camera, scene, renderer, controls;

			const clock = new THREE.Clock();

			init();
			animate();

			function init() {

				container = document.createElement( 'div' );
				document.body.appendChild( container );

				camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 15000 );
				camera.position.z = 1000;

				scene = new THREE.Scene();
				scene.fog = new THREE.Fog( 0x000000, 1, 15000 );

				const pointLight = new THREE.PointLight( 0xff2200 );
				pointLight.position.set( 0, 0, 0 );
				scene.add( pointLight );

				const dirLight = new THREE.DirectionalLight( 0xffffff );
				dirLight.position.set( 0, 0, 1 ).normalize();
				scene.add( dirLight );

				const geometry = [

					[ new THREE.IcosahedronGeometry( 100, 16 ), 50 ],
					[ new THREE.IcosahedronGeometry( 100, 8 ), 300 ],
					[ new THREE.IcosahedronGeometry( 100, 4 ), 1000 ],
					[ new THREE.IcosahedronGeometry( 100, 2 ), 2000 ],
					[ new THREE.IcosahedronGeometry( 100, 1 ), 8000 ]

				];

				const material = new THREE.MeshLambertMaterial( { color: 0xffffff, wireframe: true } );

				for ( let j = 0; j < 1000; j ++ ) {

					const lod = new THREE.LOD();

					for ( let i = 0; i < geometry.length; i ++ ) {

						const mesh = new THREE.Mesh( geometry[ i ][ 0 ], material );
						mesh.scale.set( 1.5, 1.5, 1.5 );
						mesh.updateMatrix();
						mesh.matrixAutoUpdate = false;
						lod.addLevel( mesh, geometry[ i ][ 1 ] );

					}

					lod.position.x = 10000 * ( 0.5 - Math.random() );
					lod.position.y = 7500 * ( 0.5 - Math.random() );
					lod.position.z = 10000 * ( 0.5 - Math.random() );
					lod.updateMatrix();
					lod.matrixAutoUpdate = false;
					scene.add( lod );

				}


				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				container.appendChild( renderer.domElement );

				//

				controls = new FlyControls( camera, renderer.domElement );
				controls.movementSpeed = 1000;
				controls.rollSpeed = Math.PI / 10;

				//

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			function animate() {

				requestAnimationFrame( animate );
				render();

			}

			function render() {

				controls.update( clock.getDelta() );

				renderer.render( scene, camera );

			}

		</script>

	</body>
</html>
